V.R. Post Box

This VR Post Office Wall box has interested me ever since I had to find it while on a car treasure hunt many years ago. Only a mile or so from my house it must have served a very small community at the time it was fitted which by definition must have been in the late 1800s or early 1900s.
It is always kept beautifully painted and must have many layers of red paint on it by now - it is still in use as I passed it today by coincidence just as the postman was emptying it. I wonder if it has its original lock?